Arthur francis berry



A. F. BERRY. MAGNETLC MATERIAL SUITABLE FOR USE IN STATIC TRANSFORMERS AND OTHER ELECTRICAL APPARATUS. APPUCATLON FILED EAR-1,19%-

1 ,3 1 3,054 I Patented Aug. 12, 1919.

CL 9". 15 Cl mmmmmwxm UNITED STATES PATENT OFFICE.

ARTHUR FRANCIS BERRY, OF LONDON, ENGLAND.

MAGNETIC MATERIAL SUITABLE FOR USE IN STATIC TRANSFORMERS AND OTHER ELECTRICAL APPARATUS.

Application filed January 7, 1918.

To all tchom it may concern:

Be it known that I, Ali'rnou Fiuncis BERRY, a subject of the King of Great Britam and Ireland, residing at London, England, have invented Improvements in or Itelating to Magnetic Material Suitable for Use in Static Transformers and other Electrical Apparatus, of which the following is a specification.

This invention has reference to magnetic low hysteresis value.

Although in such apparatus it is usual to laminate the magnetic core to lessen the generation therein of eddy currents in a direction at right angles to the. magnetic flux,

due to the alternation in direction of current in the winding of the apparatus, there is nevertheless a greater generation of such eddy currents than is desirable, resulting in loss of efficiency.

Now the present invention has for its object to diminish this loss of efficiency, due to the production of eddy currents, and at the same time to improve the magnetic quality of the material, particularly its permeability.

For this purpose magnetic material in the form of sheets, strips or the like, produced by rolling, whereby a more or less fibrous structure in the direction of rolling is im-' parted to the material that assists or may assist in increasing the permeability thereof, is grooved or treated, as by rolling, cutting or otherwise, in such a manner that it is caused to assume the form of a number of parallel lengths that are magnetically connected together sidewise through portions of the sheet or strip'of reduced cross section and are separated at other parts by a medium having a high electrical resistance so that conside able resistance will be offeredto the passage of electric currents in a direction transverse to the length of the sheet or strip material without interfering with the passage of magnetic flux lengthwise through the parallel portions of such sheet or strip. The resistance medium may be 'airbut 1n order to avoid the use Specification of Letters Patent.

Patented Aug. 12, 1919.

Serial No. 210,734.

of separate sheets of resistance material between adjacent sheets or strips of the grooved magnetic material, when assembling the same to form a transformer or other clcctro-imignetic apparatus, it is preferred to cover the grooved sheets on both Sl(l(S with a thin, firmly adherent layer or film of resistance material. To firmly fix or lock the resistance material in the grooves and over the surfaces of the intervening ribs or lengths of magnetic material, the sheet or strip material may advantageously be subjected to compression so as to close up the grooves and nip the insulating material in place and at the same time impart a smooth flat surface to each side of the sheet or strip.

In this way there is produced sheet or strip magnetic material of greater electrical resistance in one direction than in another. y

In the accompanying illustrative drawings, Figures 1, 2 and 3 show partly in end elevation and partly in cross section, means for producing magnetic material according to the invention; Figs. 4 and 5 show in plan and end elevation a grooved sheet or strip of magnetic material according to the invention. The figures are not to scale.

According to one method of producing magnetic material a according to the invention, sheet or strip magnetic material is heated to a suitable temperature to cause a thin, firmly adherent layer or film of iron oxid to be formed on each side thereof and While in the heated state it. is passed between a pair of grooving rolls 5 and c (Fig; 1) so as to form at its opposite sides, similar longitudinal grooves a that extend nearly through the thicknessof the sheet and leave intervening parallel ribs a of metal. a are the portions of sheet metal of reduced thickness connecting the ribs o The grooved sheet or strip a, preferably While still in a heated condition, is passed between one or more pairs of flattening rolls 6 and f'(Fig. 2) that serve to flatten the ribs (1 on one side only, the opposite side being flat. Fig. 3 shows rollers suitable for this purpose.

Figs. 4 and 5 show in plan and end view a strip or sheet of iron after it has been passed between a pair of grooving arid fiattening rolls, such as shown in Figs. 1 and 2.

Sheets or strips of magnetic material produced as described may be of various thicknesses' to suit requirement, but usually will be of about the thickness of the sheet or strip magnetic material ordinarily used in static transformers and similar alternating current apparatus. The thickness shown in the drawings is much exaggerated.

The invention can be applied to sheets or strips of magnetic material of various kinds and such material can be used in alternating electrical apparatus of different types.

\Vhat I claim is 1. Magnetic material in sheet, strip or like form and suitable for use in static transformers or other electrical apparatus, comprising, a number of parallel lengths magnetically connected together sidewise through portions of the sheet or strip material of reduced cross section or thickness, substantially as described for the purpose set forth.

2. Magnetic material according to the preceding claim, wherein the parallel lengths of magnetic material are separated from each other laterally of the connecting material between them by a medium having a high electrical resistance, substantially as described.

3. Magnetic material according to the preceding claims covered with a thin firmly adherent layer or film of resistance material, substantially as described.

4. Grooved material according to the preceding claim' wherein the layer or film of resistance material is composed of iron oxid, substantially as described.

5. Grooved material according-to the preceding claim, wherein the layer or film of resistance material between the parallel lengths of magnetic material is locked in place by compression of such parallel lengths, substantially as described.

6. The manufacture of magnetic material of the kind referred to in claim 1, according to which sheet or strip material is subjected to a grooving treatment so as to form the parallel lengths of metal connected magnetically together sidewise through portions of the strip of reduced thickness, substantially as described.

7. The manufacture of magnetic material of the kind referred to in claim 1, according to which sheet or strip magnetic 'material is grooved by rolling pressure so as to form the parallel lengths of metal connected magnetically together sideWise through portions of the strip of reduced thickness, substantially as described.

8. The manufacture of magnetic material of the kind referred to in claim 1, according to which sheet or strip magneticmaterial is heated to a temperature to cause a thin firmly adherent layer or film of iron oxid to be formed thereon and While in the heated state is passed between rolls so as to form in such material at one or both sides thereof, grooves that extend nearly through the thickness of the sheet or strip and intervening parallel ribs of metal, substantially as described.

9. The manufacture of magnetic material according to preceding claim, wherein the grooved sheet or strip material With layer or film of iron oxid thereon is, after being grooved, passed between one or more-pairs of flattening rolls so as to flatten the ribs of metal and close the grooves between them more or less and lock the layer or film of iron oxid? therein, substantially as described for the purpose set forth.

Signed at London, England, this 10th day of December, 1917.

ARTHUR FRANCIS BERRY. 

